To update that number, the new turbocharged engines required in Formula 1 since 2014 are much quieter (to some fans' dismay), maxing out around 100 dB.
http://www.marca.com/2014/01/30/motor/formula1/1391085772.ht... (Spanish)
http://www.marca.com/2014/01/30/motor/formula1/1391085772.ht... (Spanish)
I grew up near a F1 track during the "big bang" turbo era (1,350+HP from a 1.5 litre engine that would only last 3 alps in qualifying trim)[1]. I'm pretty sure we'll never hear engines like those in circuit races again, and I'm not sure that's a bad thing.
[1] http://en.wikipedia.org/wiki/Formula_One_engines#1966.E2.80....